1. Field of the Invention
The present invention relates to an improved apparatus for editing tree structures in display. The tree structures consisting of a plurality of objects and lines connecting respective objects to one another and displayed on a screen of display means.
2. Description of the Related Art
A tree structure or a directed tree is a directed graph which has no closed circuit, and only one node called root forming no end point of any branch with all nodes other than the root each having an end point of only one branch.
The tree structures have been heretofore used for expressing dependency relationship, inheritance relationship or the like among various objects. In other words, dependency relationship, inheritance relationship or the like is expressed by branches with the objects as nodes. An apparatus for editing displayed tree structures is an apparatus for displaying the tree structures on a screen and for executing deletion, creation, addition, move or the like of the objects in the trees interactively by using an electronic computer.
In such an apparatus for editing displayed tree structures, an operation as described in following items (1) or (2) has been heretofore implemented when move of an object is performed.
(1) First, an operator selects an object which is desired to be moved, then the computer copies the indication of this object in a buffer on a memory and deletes the object indication from the screen at the same time. Next, the operator selects a desired destination, then the computer pastes the object indication copied in the buffer on the memory at the destination. (As disclosed, for example, in Nexpert Object provided by Nuron Data Company.)
(2) First, an operator selects an object desired to be moved and a branch connected to its parent object, then the computer deletes them. Thereafter, the object is connected to a parent object at the desired destination by means of a branch. (As shown in JP-A-2-202620).
In the operation in the item (1) described above, however, the object desired to be moved is erased once from the screen. Therefore, the operator has to remember which object is being presently moved, thus compelling excessive burden in continuing an intellectual work.
Further, although the object during move is always displayed on a screen in the operation in the item (2) described above, it is required to repeat deletions and drawings of branches by the number of moving objects in case a plurality of objects are moved to one different parent, thus still requiring an excessive intellectual work.